diff --git a/spring-test/src/main/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessor.java b/spring-test/src/main/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessor.java
index af12c936d2..014c2f7082 100644
--- a/spring-test/src/main/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessor.java
+++ b/spring-test/src/main/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessor.java
@@ -60,6 +60,7 @@ import org.springframework.util.Assert;
  * @author Simon Baslé
  * @author Stephane Nicoll
  * @author Sam Brannen
+ * @author Yanming Zhou
  * @since 6.2
  */
 class BeanOverrideBeanFactoryPostProcessor implements BeanFactoryPostProcessor, Ordered {
@@ -169,8 +170,10 @@ class BeanOverrideBeanFactoryPostProcessor implements BeanFactoryPostProcessor,
 			}
 			else if (requireExistingBean) {
 				Field field = handler.getField();
-				throw new IllegalStateException(
-						"Unable to replace bean: there is no bean with name '%s' and type %s%s."
+				throw new IllegalStateException("""
+						Unable to replace bean: there is no bean with name '%s' and type %s%s. \
+						If the bean is defined in a @Bean method, make sure the return type is the \
+						most specific type possible (for example, the concrete implementation type)."""
 							.formatted(beanName, handler.getBeanType(), requiredByField(field)));
 			}
 			// 4) We are creating a bean by-name with the provided beanName.
@@ -258,7 +261,11 @@ class BeanOverrideBeanFactoryPostProcessor implements BeanFactoryPostProcessor,
 				String message = "Unable to select a bean to wrap: ";
 				int candidateCount = candidateNames.size();
 				if (candidateCount == 0) {
-					message += "there are no beans of type %s%s.".formatted(beanType, requiredByField(field));
+					message += """
+							there are no beans of type %s%s. \
+							If the bean is defined in a @Bean method, make sure the return type is the \
+							most specific type possible (for example, the concrete implementation type)."""
+								.formatted(beanType, requiredByField(field));
 				}
 				else {
 					message += "found %d beans of type %s%s: %s"
@@ -272,8 +279,10 @@ class BeanOverrideBeanFactoryPostProcessor implements BeanFactoryPostProcessor,
 			// We are wrapping an existing bean by-name.
 			Set<String> candidates = getExistingBeanNamesByType(beanFactory, handler, false);
 			if (!candidates.contains(beanName)) {
-				throw new IllegalStateException(
-						"Unable to wrap bean: there is no bean with name '%s' and type %s%s."
+				throw new IllegalStateException("""
+						Unable to wrap bean: there is no bean with name '%s' and type %s%s. \
+						If the bean is defined in a @Bean method, make sure the return type is the \
+						most specific type possible (for example, the concrete implementation type)."""
 							.formatted(beanName, beanType, requiredByField(field)));
 			}
 		}
@@ -297,8 +306,10 @@ class BeanOverrideBeanFactoryPostProcessor implements BeanFactoryPostProcessor,
 		int candidateCount = candidateNames.size();
 		if (candidateCount == 0) {
 			if (requireExistingBean) {
-				throw new IllegalStateException(
-						"Unable to override bean: there are no beans of type %s%s."
+				throw new IllegalStateException("""
+						Unable to override bean: there are no beans of type %s%s. \
+						If the bean is defined in a @Bean method, make sure the return type is the \
+						most specific type possible (for example, the concrete implementation type)."""
 							.formatted(beanType, requiredByField(field)));
 			}
 			return null;
diff --git a/spring-test/src/test/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessorTests.java b/spring-test/src/test/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessorTests.java
index 8b3ce3c1a6..76cb72be8b 100644
--- a/spring-test/src/test/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessorTests.java
+++ b/spring-test/src/test/java/org/springframework/test/context/bean/override/BeanOverrideBeanFactoryPostProcessorTests.java
@@ -87,7 +87,9 @@ class BeanOverrideBeanFactoryPostProcessorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to replace bean: there is no bean with name 'descriptionBean' \
-						and type java.lang.String (as required by field 'ByNameTestCase.description').""");
+						and type java.lang.String (as required by field 'ByNameTestCase.description'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
@@ -99,7 +101,9 @@ class BeanOverrideBeanFactoryPostProcessorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to replace bean: there is no bean with name 'descriptionBean' \
-						and type java.lang.String (as required by field 'ByNameTestCase.description').""");
+						and type java.lang.String (as required by field 'ByNameTestCase.description'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
@@ -146,7 +150,9 @@ class BeanOverrideBeanFactoryPostProcessorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to override bean: there are no beans of type java.lang.Integer \
-						(as required by field 'ByTypeTestCase.counter').""");
+						(as required by field 'ByTypeTestCase.counter'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
diff --git a/spring-test/src/test/java/org/springframework/test/context/bean/override/convention/TestBeanTests.java b/spring-test/src/test/java/org/springframework/test/context/bean/override/convention/TestBeanTests.java
index d771af6333..08600f7c09 100644
--- a/spring-test/src/test/java/org/springframework/test/context/bean/override/convention/TestBeanTests.java
+++ b/spring-test/src/test/java/org/springframework/test/context/bean/override/convention/TestBeanTests.java
@@ -42,7 +42,9 @@ public class TestBeanTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to replace bean: there is no bean with name 'beanToOverride' \
-						and type java.lang.String (as required by field 'FailureByNameLookup.example').""");
+						and type java.lang.String (as required by field 'FailureByNameLookup.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
@@ -54,7 +56,9 @@ public class TestBeanTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to replace bean: there is no bean with name 'beanToOverride' \
-						and type java.lang.String (as required by field 'FailureByNameLookup.example').""");
+						and type java.lang.String (as required by field 'FailureByNameLookup.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
@@ -64,8 +68,9 @@ public class TestBeanTests {
 		assertThatIllegalStateException()
 				.isThrownBy(context::refresh)
 				.withMessage("""
-						Unable to override bean: there are no beans of \
-						type %s (as required by field '%s.example').""",
+						Unable to override bean: there are no beans of type %s (as required by field '%s.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""",
 						String.class.getName(), FailureByTypeLookup.class.getSimpleName());
 	}
 
diff --git a/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoBeanConfigurationErrorTests.java b/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoBeanConfigurationErrorTests.java
index 1182a8afc5..3090ccd10d 100644
--- a/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoBeanConfigurationErrorTests.java
+++ b/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoBeanConfigurationErrorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -42,7 +42,9 @@ class MockitoBeanConfigurationErrorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to replace bean: there is no bean with name 'beanToOverride' \
-						and type java.lang.String (as required by field 'FailureByNameLookup.example').""");
+						and type java.lang.String (as required by field 'FailureByNameLookup.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
@@ -54,7 +56,9 @@ class MockitoBeanConfigurationErrorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to replace bean: there is no bean with name 'beanToOverride' \
-						and type java.lang.String (as required by field 'FailureByNameLookup.example').""");
+						and type java.lang.String (as required by field 'FailureByNameLookup.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
@@ -65,7 +69,9 @@ class MockitoBeanConfigurationErrorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to override bean: there are no beans of \
-						type java.lang.String (as required by field 'FailureByTypeLookup.example').""");
+						type java.lang.String (as required by field 'FailureByTypeLookup.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test
diff --git a/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoSpyBeanConfigurationErrorTests.java b/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoSpyBeanConfigurationErrorTests.java
index efdbf88733..c1564c1dd3 100644
--- a/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoSpyBeanConfigurationErrorTests.java
+++ b/spring-test/src/test/java/org/springframework/test/context/bean/override/mockito/MockitoSpyBeanConfigurationErrorTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,7 +41,9 @@ class MockitoSpyBeanConfigurationErrorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to wrap bean: there is no bean with name 'beanToSpy' and \
-						type java.lang.String (as required by field 'ByNameSingleLookup.example').""");
+						type java.lang.String (as required by field 'ByNameSingleLookup.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 		}
 
 	@Test
@@ -52,7 +54,9 @@ class MockitoSpyBeanConfigurationErrorTests {
 				.isThrownBy(context::refresh)
 				.withMessage("""
 						Unable to select a bean to wrap: there are no beans of type java.lang.String \
-						(as required by field 'ByTypeSingleLookup.example').""");
+						(as required by field 'ByTypeSingleLookup.example'). \
+						If the bean is defined in a @Bean method, make sure the return type is the most \
+						specific type possible (for example, the concrete implementation type).""");
 	}
 
 	@Test